Just thought I'd share my experience with my Nexus 5. I was having issues with the camera not focussing and therefore not reading the scan sheets. I found out that by double tapping the screen the camera will focus and scan.

Thought I would put this out there in case there are others who are having the same issue.

In the app if you go to settings and then Sync Frequency is it set? Try setting it to 1 minute and see if that helps. Mine seems to be syncing OK and I just changed that setting. Let me know if that helps.

That's one I've never come across. Are you making the key on the mobile app or via the website? If you're making the key on the website try making the key via the mobile app. Personally I prefer keying quizzes on the mobile app.

If you're already keying the quiz on the mobile app send in a support ticket and hopefully they can figure out what's going on.

Two things to consider:1. Lighting. Try scanning in a different room or under different light. This has worked for me in the past when I've had issues similar to yours.2. Filling in the bubbles. If changing the lighting doesn't help try going over the bubbles with a black sharpie. This has also helped me in the past.

Let me know if this helped. If not we can definitely troubleshoot some more. Thanks for using QuickKey!